BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA

WEDNESDAY MAY 12, 2021
ALL TIMES ARE IN EASTERN STANDARD TIME
SUNRISE: 0426E
SUNSET:  1856E

INCREASING CLOUDS WITH A COOL WESTERLY BREEZE....

Today we observed almost clear skies this morning
turning into a near overcast as the day went on.
Visibility was great at 75 miles, and conditions
were dry considering the dew point was near freezing
despite temperatures in the low 60's. The humidity was
33% at the 1 P.M. observation.  
 
The average wind speed is around 10 mph from the west
with a gust of 29 mph since 7 A.M.

The high so far today is 65F, this is the same as the
normal high. The low since midnight is 41F, which
is 6 degrees below the daily normal low of 47F.


PRELIMINARY STATS FOR APRIL 2021

TEMPERATURE, Deg. F
Avg. Max. 57.2 [+1.5]
Avg. Min. 37.8 [+0.1]
Mean      47.5 [+0.8]
24-hour corrected mean: 47.0
Max. for month: 75F on the 10th
Min. for month: 23F on the 3rd

HEATING DEGREE DAYS
Total heating units:    519 [-32]
Total for the season:  5341 [-694]
Total for last season: 5521

PRECIPITATION, Inches
Total: 4.89 [+0.45]
Greatest in 24 hrs: 2.45 ins. on the 15th-16th

SNOWFALL, Inches
Total: 3.6 [+0.6]
Greatest in 24 hrs: 3.6 ins. on the 16th

WIND, mph
Avg. uncorrected wind speed: 12.1 mph
Avg. corrected wind speed:   12.5 mph
Prevailing wind direction:   WNW [16%]
Peak gust and direction:     58 WNW on the 30th

SUNSHINE:
Campbell-Stokes card minutes: 12444 minutes of a possible 23250 or 54%
Astronomical total minutes: 12904 minutes of a possible 24128 or 53%


Today's Observations:

7 A.M.
Weather: Few cumulus and cirrostratus
Temperature: 48F; Dew Point: 34F; Relative Humidity: 58%
Wind: WNW at 13G20 kts
Sea-level pressure: 30.03 in/Hg, steady, then rising
Visibility: 75 miles
6-hr Max temp: 48F
6-hr Min temp: 41F
24-hr Precip: 0.00 ins.
24-hr Snow: 0.0 ins.
Snow Depth: 0.0 ins.
BHO SA 1155 CLR 75 168/48/34/2913G20/003/ FEW CU/CS ALQDS/
8/105 51011 10048 20041

10 A.M.
Weather: Broken cumulus and cirrostratus
Temperature: 58F; Dew Point: 37F; Relative Humidity: 45%
Wind: WNW @ 10 kts
Sea-level pressure: 30.06 in Hg; rising steadily
Visibility: 75 miles
3-hr Precip: 0.00 ins.
3-hr Snow: 0.0 ins.
BHO SA 1455 50 BKN 250 BKN 75 178/58/37/3010/006/ 8/108 53010

1 P.M.
Weather: Broken altocumulus
Temperature: 60F, Dew point: 33F; Relative Humidity: 35%
Wind: NW @ 8 kts
Sea-level pressure: 30.07 in Hg; falling then rising
Visibility: 75 miles
6-hr Max temp: 65F
6-hr Min temp: 48F
6-hr Precip: 0.00 ins.
6-hr Snow: 0.0 ins.
Snow Depth: 0 ins.
BHO SA 1755 70 BKN 75 181/60/33/3408/007/ 8/070 50003 10065
20048


SUMMARY FOR TUESDAY, MAY 11, 2021

TEMPERATURE (DEGREES F)
MAX.......63     NORMAL.....65
MIN.......45     NORMAL.....46
MEAN......54     NORMAL.....56

DEPARTURE FROM 30-YEAR (1981-2010) NORMAL....... -2
TOTAL DEPARTURE FOR THE MONTH...................-19 [-1.9 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL THRU JUN)
TOTAL HEATING UNITS FOR YESTERDAY...............11  DEPARTURE.......+2
TOTAL HEATING UNITS FOR THE MONTH..............137  DEPARTURE......+14
TOTAL HEATING UNITS FOR THE SEASON............5478  DEPARTURE.....-680
TOTAL HEATING UNITS LAST SEASON TO DATE.......5664  DEPARTURE.....-186

COOLING DEGREE DAYS (SEASON JAN THRU DEC)
TOTAL COOLING UNITS FOR YESTERDAY............... 0  DEPARTURE....... 0
TOTAL COOLING UNITS FOR THE MONTH............... 0  DEPARTURE.......-3
TOTAL COOLING UNITS FOR THE SEASON.............. 0  DEPARTURE.......-5
TOTAL COOLING UNITS LAST SEASON TO DATE......... 2  DEPARTURE.......-2

PEAK WIND GUST (MPH):
                     420C/Official..............38 WNW @ 5:31 P.M.
                     AEROVANE (south tower).....41 WNW @ 4:39 P.M.
                     ASOS.......................38 WNW @ 5:31 P.M.
                     DAVIS #1...................39 W   @ 4:38 P.M.
                     DAVIS #2 (south tower).....40 WNW @ 4:38 P.M.
                     RMY........................41     @ 4:37 P.M.
                     VECTOR.....................45     @ 4:38 P.M.
                     MERLIN.....................38

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL..................30 WNW @  4:40 P.M.
MAXIMUM 2-MINUTE ASOS AVERAGE...................29 W   @  4:40 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE...............31 WNW @  4:40 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE...............31 WNW @  4:40 P.M.
MAXIMUM 2-MINUTE RMY AVERAGE....................27 WNW @  4:37 P.M.
MAXIMUM 2-MINUTE VECTOR AVERAGE.................29     @  4:37 P.M.

AVERAGE WIND SPEED AND DIRECTION:
                     CONTACTING/OFFICIAL......15.7 WNW [377 total miles]
                     ASOS.....................15.1
                     DAVIS #1.................16.1 WNW
                     DAVIS #2.................16.4 WNW
                     RMY......................14.1 WNW
                     VECTOR...................15.3


PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M.......0.00  DEPARTURE....-0.12
                             ASOS.............0.00
TOTAL PRECIPITATION FOR THE MONTH.............1.78  DEPARTURE....+0.44
                             ASOS.............1.73
TOTAL PRECIPITATION FOR THE YEAR.............16.84  DEPARTURE....-3.05
                              ASOS...........17.01


PRELIMINARY CLIMATE SUMMARY FOR MAY CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/PEAK GUST/AERO/RMY GUST
AERO: Aerovane wind recording system gust
RMY:  R.M. Young wind gust recording system
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
M:    Missing data

05/01   62/38/50/-3/0.06/0.0/.../..       31 WNW  AERO 35 WNW  RMY 40
05/02   76/48/62/+9/0.01/0.0/.../..       41 SW   AERO 41 SW   RMY 46
05/03   67/48/58/+5/0.07/0.0/.../..       21 E    AERO 20 E    RMY 20
05/04   50/44/47/-7/0.78/0.0/.../..       36 NNE  AERO 32 NNE  RMY 37
05/05   48/44/46/-8/0.45/0.0/.../..       18 ESE  AERO 14 ESE  RMY 17
05/06   64/45/55/+1/0.00/0.0/.../..       33 NW   AERO 38 NNW  RMY 39
05/07   61/43/52/-3/0.00/0.0/.../..       28 ESE  AERO 22 ESE  RMY 26
05/08   54/40/47/-8/0.00/0.0/.../..       24 SSW  AERO 23 SSW  RMY 25
05/09   66/42/54/-1/T/0.0/.../..          30 SW   AERO 29 SW   RMY 34
05/10   60/45/53/-2/0.39/0.0/.../..       21 W    AERO 20 W    RMY 20
05/11   63/45/54/-2/0.00/0.0/.../..       38 WNW  AERO 41 WNW  RMY 41

05/12 The low since midnight is 41F, the daily normal low is 47F
 

DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated)

RECORDS FOR MAY 12
HIGH 88F IN 2001
LOW 29F IN 1907
PRECIP 1.49 INCHES IN 1968
SNOW TRACE IN 2019
PEAK GUST 76 MPH S IN 1974

RECORDS FOR MAY 13
HIGH 85F IN 1947
LOW 32F IN 2020
PRECIP 2.39 INCHES IN 2006
PEAK GUST 49 MPH NNW IN 1965

TODAY'S REPORT PREPARED BY: Benjamin Turner